opostdaisy.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

    int		i;			/* loop index */

/*
 *
 * Clears all horizontal and vertical tab stops.
 *
 */

    for ( i = 0; i < ROWS; i++ )
	htabstops[i] = OFF;

    for ( i = 0; i < COLUMNS; i++ )
	vtabstops[i] = OFF;

}   /* End of cleartabs */

/*****************************************************************************/

formfeed()

{

/*
 *
 * Called whenever we've finished with the last page and want to get ready for the
 * next one. Also used at the beginning and end of each input file, so we have to
 * be careful about what's done. I've added a simple test before the showpage that
 * should eliminate the extra blank page that was put out at the end of many jobs,
 * but the PAGES comments may be wrong.
 *
 */

    if ( fp_out == stdout )		/* count the last page */
	printed++;

    endline();				/* print the last line */

    fprintf(fp_out, "cleartomark\n");
    if ( feof(fp_in) == 0 || markedpage == TRUE )
	fprintf(fp_out, "showpage\n");
    fprintf(fp_out, "saveobj restore\n");
    fprintf(fp_out, "%s %d %d\n", ENDPAGE, page, printed);

    if ( ungetc(getc(fp_in), fp_in) == EOF )
	redirect(-1);
    else redirect(++page);

    fprintf(fp_out, "%s %d %d\n", PAGE, page, printed+1);
    fprintf(fp_out, "/saveobj save def\n");
    fprintf(fp_out, "mark\n");
    writerequest(printed+1, fp_out);
    fprintf(fp_out, "%d pagesetup\n", printed+1);

    vgoto(topmargin);
    hgoto(leftmargin);

    markedpage = FALSE;

}   /* End of formfeed */

/*****************************************************************************/

linefeed()

{

    int		line = 0;		/* current line - based on ovmi */

/*
 *
 * Adjust our current vertical position. If we've passed the bottom of the page
 * or exceeded the number of lines per page, print it and go to the upper left
 * corner of the next page. This routine is also called from carriage() if crislf
 * is ON.
 *
 */

    vmot(vmi);

    if ( lfiscr == ON )
	hgoto(leftmargin);

    if ( linespp > 0 )			/* means something so see where we are */
	line = vpos / ovmi + 1;

    if ( vpos > bottommargin || line > linespp )
	formfeed();

}   /* End of linefeed */

/*****************************************************************************/

carriage()

{

/*
 *
 * Handles carriage return character. If crislf is ON we'll generate a line feed
 * every time we get a carriage return character.
 *
 */

    if ( shadowprint == ON )		/* back to normal mode */
	changefont(fontname);

    advance = 1;
    shadowprint = OFF;

    hgoto(leftmargin);

    if ( crislf == ON )
	linefeed();

}   /* End of carriage */

/*****************************************************************************/

htab()

{

    int		col;			/* 'column' we'll be at next */
    int		i;			/* loop index */

/*
 *
 * Tries to figure out where the next tab stop is. Wasn't positive about this
 * one, since hmi can change. I'll assume columns are determined by the original
 * value of hmi. That fixes them on the page, which seems to make more sense than
 * letting them float all over the place.
 *
 */

    endline();

    col = hpos/ohmi + 1;
    for ( i = col; i < ROWS; i++ )
	if ( htabstops[i] == ON )  {
	    col = i;
	    break;
	}   /* End if */

    hgoto(col * ohmi);
    lastx = hpos;

}   /* End of htab */

/*****************************************************************************/

vtab()

{

    int		line;			/* line we'll be at next */
    int		i;			/* loop index */

/*
 *
 * Looks for the next vertical tab stop in the vtabstops[] array and moves to that
 * line. If we don't find a tab we'll just move down one line - shouldn't happen.
 *
 */

    endline();

    line = vpos/ovmi + 1;
    for ( i = line; i < COLUMNS; i++ )
	if ( vtabstops[i] == ON )  {
	    line = i;
	    break;
	}   /* End if */

    vgoto(line * ovmi);

}   /* End of vtab */

/*****************************************************************************/

backspace()

{

/*
 *
 * Moves backwards a distance equal to the current value of hmi, but don't go
 * past the left margin.
 *
 */

    endline();

    if ( hpos - leftmargin >= hmi )
	hmot(-hmi);
    else hgoto(leftmargin);		/* maybe just ignore the backspace?? */

    lastx = hpos;

}   /* End of backspace */

/*****************************************************************************/

escape()

{

    int		ch;			/* control character */

/*
 *
 * Handles special codes that are expected to follow an escape character. The
 * initial escape character is followed by one or two bytes.
 *
 */

    switch ( ch = getc(fp_in) ) {
	case 'T':			/* top margin */
		topmargin = vpos;
		break;

	case 'L':			/* bottom margin */
		bottommargin = vpos;
		break;

	case 'C':			/* clear top and bottom margins */
		bottommargin = BOTTOMMARGIN;
		topmargin = TOPMARGIN;
		break;

	case '9':			/* left margin */
		leftmargin = hpos;
		break;

	case '0':			/* right margin */
		rightmargin = hpos;
		break;

	case '1':			/* set horizontal tab */
		htabstops[hpos/ohmi] = ON;
		break;

	case '8':			/* clear horizontal tab at hpos */
		htabstops[hpos/ohmi] = OFF;
		break;

	case '-':			/* set vertical tab */
		vtabstops[vpos/ovmi] = ON;
		break;

	case '2':			/* clear all tabs */
		cleartabs();
		break;

	case '\014':			/* set lines per page */
		linespp = getc(fp_in);
		break;

	case '\037':			/* set hmi to next byte minus 1 */
		hmi = HSCALE * (getc(fp_in) - 1);
		break;

	case 'S':			/* reset hmi to default */
		hmi = ohmi;
		break;

	case '\011':			/* move to column given by next byte */
		hgoto((getc(fp_in)-1) * ohmi);
		break;

	case '?':			/* do carriage return after line feed */
		lfiscr = ON;
		break;

	case '!':			/* don't generate carriage return */
		lfiscr = OFF;
		break;

	case '5':			/* forward print mode */
		advance = 1;
		break;

	case '6':			/* backward print mode */
		advance = -1;
		break;

	case '\036':			/* set vmi to next byte minus 1 */
		vmi = VSCALE * (getc(fp_in) - 1);
		break;

	case '\013':			/* move to line given by next byte */
		vgoto((getc(fp_in)-1) * ovmi);
		break;

	case 'U':			/* positive half line feed */
		vmot(vmi/2);
		break;

	case 'D':			/* negative half line feed */
		vmot(-vmi/2);
		break;

	case '\012':			/* negative line feed */
		vmot(-vmi);
		break;

	case '\015':			/* clear all margins */
		bottommargin = BOTTOMMARGIN;
		topmargin = TOPMARGIN;
		leftmargin = BOTTOMMARGIN;
		rightmargin = RIGHTMARGIN;
		break;

	case 'E':			/* auto underscore - use italic font */
		changefont("/Courier-Oblique");
		break;

	case 'R':			/* disable auto underscore */
		changefont(fontname);
		break;

	case 'O':			/* bold/shadow printing */
	case 'W':
		changefont("/Courier-Bold");
		shadowprint = ON;
		break;

	case '&':			/* disable bold printing */
		changefont(fontname);
		shadowprint = OFF;
		break;

	case '/':			/* ignored 2 byte escapes */
	case '\\':
	case '<':
	case '>':
	case '%':
	case '=':
	case '.':
	case '4':
	case 'A':
	case 'B':
	case 'M':
	case 'N':
	case 'P':
	case 'Q':
	case 'X':
	case '\010':
		break;

	case ',':			/* ignored 3 byte escapes */
	case '\016':
	case '\021':
		getc(fp_in);
		break;

	case '3':			/* graphics mode - should quit! */
	case '7':
	case 'G':
	case 'V':
	case 'Y':
	case 'Z':
		error(FATAL, "graphics mode is not implemented");
		break;

	default:
		error(FATAL, "missing case for escape o%o\n", ch);
		break;
    }	/* End switch */

}   /* End of escape */

/*****************************************************************************/

vmot(n)

    int		n;			/* move this far vertically */

{

/*
 *
 * Move vertically n units from where we are.
 *
 */

    vpos += n;

}   /* End of vmot */

/*****************************************************************************/

vgoto(n)

    int		n;			/* new vertical position */

{

/*
 *
 * Moves to absolute vertical position n.
 *
 */

    vpos = n;

}   /* End of vgoto */

/*****************************************************************************/

hmot(n)

    int		n;			/* move this horizontally */

{

/*
 *
 * Moves horizontally n units from our current position.
 *
 */

    hpos += n * advance;

    if ( hpos < leftmargin )
	hpos = leftmargin;

}   /* End of hmot */

/*****************************************************************************/

hgoto(n)

    int		n;			/* go to this horizontal position */

{

/*
 *
 * Moves to absolute horizontal position n.
 *
 */

    hpos = n;

}   /* End of hgoto */

/*****************************************************************************/

changefont(name)

    char	*name;

{

/*
 *
 * Changes the current font. Used to get in and out of auto underscore and bold
 * printing.
 *
 */

    endline();
    fprintf(fp_out, "%s f\n", name);

}   /* End of changefont */

/*****************************************************************************/

startline()

{

/*
 *
 * Called whenever we want to be certain we're ready to start pushing characters
 * into an open string on the stack. If stringcount is positive we've already
 * started, so there's nothing to do. The first string starts in column 1.
 *
 */

    if ( stringcount < 1 )  {
	putc('(', fp_out);
	stringstart = lastx = hpos;
	lasty = vpos;
	lasthmi = hmi;
	lastc = -1;
	prevx = -1;
	stringcount = 1;
    }	/* End if */

}   /* End of startline */

/*****************************************************************************/

endline()

{

/*
 *
 * Generates a call to the PostScript procedure that processes the text on the
 * the stack - provided stringcount is positive.
 *
 */

    if ( stringcount > 0 )
	fprintf(fp_out, ")%d %d %d t\n", stringstart, lasty, lasthmi);

    stringcount = 0;

}   /* End of endline */

/*****************************************************************************/

endstring()

{

/*
 *
 * Takes the string we've been working on and adds it to the output file. Called
 * when we need to adjust our horizontal position before starting a new string.
 * Also called from endline() when we're done with the current line.
 *
 */

    if ( stringcount > 0 )  {
	fprintf(fp_out, ")%d(", stringstart);
	lastx = stringstart = hpos;
	stringcount++;
    }	/* End if */

}   /* End of endstring */

/*****************************************************************************/

oput(ch)

    int		ch;			/* next output character */

{

/*
 *
 * Responsible for adding all printing characters from the input file to the
 * open string on top of the stack. The only other characters that end up in
 * that string are the quotes required for special characters. Reverse printing
 * mode hasn't been tested but it should be close. hpos and lastx should disagree
 * each time (except after startline() does something), and that should force a
 * call to endstring() for every character.
 *
 */

    if ( stringcount > 100 )		/* don't put too much on the stack */
	endline();

    if ( vpos != lasty )
	endline();

    if ( advance == -1 )		/* for reverse printing - move first */
	hmot(hmi);

    startline();

    if ( lastc != ch || hpos != prevx )  {
	if ( lastx != hpos )
	    endstring();

	if ( ch == '\\' || ch == '(' || ch == ')' )
	    putc('\\', fp_out);
	putc(ch, fp_out);

	lastc = ch;
	prevx = hpos;
	lastx += lasthmi;
    }	/* End if */

    if ( advance != -1 )
	hmot(hmi);

    markedpage = TRUE;

}   /* End of oput */

/*****************************************************************************/

redirect(pg)

    int		pg;			/* next page we're printing */

{

    static FILE	*fp_null = NULL;	/* if output is turned off */

/*
 *
 * If we're not supposed to print page pg, fp_out will be directed to /dev/null,
 * otherwise output goes to stdout.
 *
 */

    if ( pg >= 0 && in_olist(pg) == ON )
	fp_out = stdout;
    else if ( (fp_out = fp_null) == NULL )
	fp_out = fp_null = fopen("/dev/null", "w");

}   /* End of redirect */

/*****************************************************************************/